Cymodocea serrulata has a wide Indo-Pacific distribution. In the Pacific, it is found from southern Japan, Taiwan and Hainan, China, the Philippines, Indonesia, and Malaysia extending to the southern tip of Vietnam and the Gulf of Thailand and across insular Southeast Asia to New Caledonia, northern Australia and across Micronesia. In the Indian Ocean, it is found from Chabjuwardoo Bay in mid-Western Australia extending across the Timor Sea, the south coast of Indonesia, and throughout the Andaman Sea. In India, it is found from the Coromandel Coast to the Malabar Coast and in the Lakshadweep Islands. It ranges from the Red Sea south to the east coast of South Africa to Madagascar and the islands of the western Indian Ocean.